[sdiy] Korg MS-50 VCF similar to Yamaha GX-1 VCF?

[Aaron Lanterman]

It's hard to read the schematic:

http://www.physicsenterprises.andrews.edu/diy_archive/schematics/filters/images/ms50filt.gif

But it seems there's the GX-1 diode ring... what's interesting there is 
that Yamaha had a patent on that diode ring when mixed with a Sallen-Key,
and this looks Sallen-Keyish..

So I wonder if Korg licensed it, or if not, if Korg could have been 
considered infringing on Yamaha's patent.

- Aaron

-----------------------------------------------------------------------------

Dr. Aaron Lanterman, Asst. Prof.       Voice:  404-385-2548
School of Electrical and Comp. Eng.    Fax:    404-894-8363
Georgia Institute of Technology        E-mail: lanterma at ece.gatech.edu
Mail Code 0250                         Web:    users.ece.gatech.edu/~lanterma
Atlanta, GA 30332                      Office: GCATT 334B